//
//  SDLContext.swift
//  Tun
//
//  Created by 安礼成 on 2024/2/29.
//

import Foundation
import NetworkExtension
import NIOCore

// 上下文环境变量，全局共享
/*
1. 处理rsa的加解密逻辑
 */

func startMonitorTask(name: String, _ body: @escaping () async throws -> Void, retryDelay: Duration = .seconds(5)) -> Task<Void, Never> {
    return Task(name: name) {
        while true {
            do {
                try Task.checkCancellation()
                try await body()
            } catch is CancellationError {
                SDLLogger.log("[SDLContext] worker \(name) cancelled", for: .debug)
                break
            } catch let err {
                SDLLogger.log("[SDLContext] worker \(name) crashed: \(err.localizedDescription), will restart", for: .debug)
                do {
                    try await Task.sleep(for: retryDelay)
                } catch is CancellationError {
                    break
                } catch {
                    break
                }
            }
        }
    }
}

// 转换成ip地址
private func asIpAddress(_ ipNum: UInt32) -> String {
    return SDLUtil.int32ToIp(ipNum)
}

enum SDLContextError: Error {
    case udpHoleClosed
    
    case dnsLocalClientClosed
    case dnsLocalClientCancelled
    
    case dnsClientClosed
    case dnsClientCancelled
}

actor SDLContextActor {

    private var config: SDLConfiguration
    // nat的网络类型
    var natType: SDLNATProberActor.NatType = .blocked
    
    // AES加密，授权通过后，对象才会被创建
    private var dataCipher: CCDataCipher?
    
    // session token
    private var sessionToken: Data?
    
    // rsa的相关配置, public_key是本地生成的
    // 加密算法相关
    nonisolated let rsaCipher: RSACipher
    
    private var udpHoleService: SDLUDPHoleService?
    private var dnsService: SDLDNSService?
    private var superService: SDLSuperService?
    private var packetReaderService: SDLPacketReaderService?

    private let publicDnsServers = ["223.5.5.5", "119.29.29.29"]

    nonisolated private let puncherActor: SDLPuncherActor
    // 网络探测对象
    nonisolated private let proberActor: SDLNATProberActor
    
    // 本地ipv6地址信息探测
    private var ipv6AssistClient: SDLIPV6AssistClient?

    private let sessionManager = SessionManager()
    nonisolated private let arpServer: ArpServer
    
    // 内部socket通讯
    // 改为基于 App Group + Darwin Notification 的通知
    
    // 流量统计
    nonisolated private let flowTracer = SDLFlowTracer()
    
    nonisolated private let provider: NEPacketTunnelProvider
    
    // 处理权限控制
    private var updatePolicyTask: Task<Void, Never>?
    private let policyService: PolicyService
    
    // stunRequest任务
    private var stunRequestTask: Task<Void, Never>?

    public init(provider: NEPacketTunnelProvider, config: SDLConfiguration, rsaCipher: RSACipher) {
        self.provider = provider
        self.config = config
        self.rsaCipher = rsaCipher
        
        self.puncherActor = SDLPuncherActor()
        self.proberActor = SDLNATProberActor(addressArray: config.stunProbeSocketAddressArray)

        self.arpServer = ArpServer()

        // 权限控制
        self.policyService = PolicyService(identityId: config.identityId)
    }
    
    public func start() async {
        self.prepareTunnelNotifier()
        
        // 启动arp的定时清理任务
        await self.puncherActor.start()
        await self.arpServer.start()
        
        let dnsService = SDLDNSService(serverHost: self.config.serverHost, publicDnsServers: self.publicDnsServers) { [weak self] event in
            await self?.handleDNSEvent(event)
        }
        self.dnsService = dnsService
        await dnsService.start()

        let udpHoleService = SDLUDPHoleService(proberActor: self.proberActor) { [weak self] event in
            await self?.handleUDPHoleEvent(event)
        }
        self.udpHoleService = udpHoleService
        await udpHoleService.start(includeV6: false)

        let superService = SDLSuperService(host: self.config.serverHost) { [weak self] message in
            await self?.handleSuperMessage(message: message)
        }
        self.superService = superService
        await superService.start()
    }

    // 处理context的停止问题
    public func stop() async {
        await self.puncherActor.stop()
        await self.arpServer.stop()
        await self.sessionManager.clear()

        self.stunRequestTask?.cancel()
        self.stunRequestTask = nil

        self.updatePolicyTask?.cancel()
        self.updatePolicyTask = nil
        await self.policyService.clear()
        
        let packetReaderService = self.packetReaderService
        self.packetReaderService = nil
        await packetReaderService?.stop()

        let udpHoleService = self.udpHoleService
        self.udpHoleService = nil
        await udpHoleService?.stop()

        let dnsService = self.dnsService
        self.dnsService = nil
        await dnsService?.stop()

        let superService = self.superService
        self.superService = nil
        await superService?.stop()
        
        self.sessionToken = nil
        self.dataCipher = nil
        self.natType = .blocked
        
        await self.ipv6AssistClient?.stop()
        self.ipv6AssistClient = nil
    }

    deinit {
        SDLLogger.log("[SDLContext] deinit", for: .debug)
    }
    
}

// MARK: probe网络类型
extension SDLContextActor {
    
    private func setNatType(natType: SDLNATProberActor.NatType) {
        self.natType = natType
    }
}

// MARK: Notifier通知机制
extension SDLContextActor {
    
    private func prepareTunnelNotifier() {
        // 启动noticeClient
        // 旧的 UDP NoticeClient 已移除，改为初始化基于 App Group 的通知通道。
        SDLTunnelAppNotifier.shared.clear()
        
        SDLLogger.log("[SDLContext] tunnelAppNotifier ready")
    }
    
    private func publishTunnelEvent(code: Int? = nil, message: String) {
        SDLTunnelAppNotifier.shared.publish(code: code, message: message)
    }
}

// MARK: 数据发送
extension SDLContextActor {
    
    // 发送给super/stun节点的数据
    private func sendSuperPacket(type: SDLPacketType, data: Data) async {
        await self.sendPacket(type: type, data: data, remoteAddress: self.config.stunSocketAddress)
    }
    
    // 发送给peer的数据
    private func sendPeerPacket(type: SDLPacketType, data: Data, remoteAddress: SocketAddress) async {
        await self.sendPacket(type: type, data: data, remoteAddress: remoteAddress)
    }
    
    private func sendPacket(type: SDLPacketType, data: Data, remoteAddress: SocketAddress) async {
        await self.udpHoleService?.send(type: type, data: data, remoteAddress: remoteAddress)
    }
}

// MARK: 处理和Super之间的通讯
extension SDLContextActor {
    
    private func handleSuperMessage(message: SDLQUICInboundMessage) async {
        switch message {
        case .welcome(let welcome):
            SDLLogger.log("[SDLContext] quic welcome: \(welcome)")
            
            await self.ipv6AssistClient?.stop()
            self.ipv6AssistClient = nil
            // 尝试创建v6地址的辅助探测器
            if welcome.hasIpv6Assist {
                self.ipv6AssistClient = SDLIPV6AssistClient(assistServerInfo: welcome.ipv6Assist)
                await self.ipv6AssistClient?.start()
            }
            
            // 注册
            await self.doRegisterSuper()
            SDLLogger.log("[SDLContext] quic doRegisterSuper")
        case .pong:
            //SDLLogger.shared.log("[SDLContext] quic pong")
            ()
        case .registerSuperAck(let registerSuperAck):
            await self.handleRegisterSuperAck(registerSuperAck: registerSuperAck)
        case .registerSuperNak(let registerSuperNak):
            self.handleRegisterSuperNak(nakPacket: registerSuperNak)
        case .peerInfo(let peerInfo):
            SDLLogger.log("[SDLContext] peer message: \(peerInfo)")
            let packets = await self.puncherActor.makeRegisterPackets(peerInfo: peerInfo)
            for packet in packets {
                await self.udpHoleService?.send(type: .register, data: packet.data, remoteAddress: packet.remoteAddress)
            }
        case .event(let event):
            await self.handleEvent(event: event)
        case .policyReponse(let policyResponse):
            // 处理权限的请求问题
            await self.policyService.applyPolicyResponse(policyResponse)
        case .arpResponse(let arpResponse):
            SDLLogger.log("[SDLContext] get arp response: \(arpResponse)")
            await self.arpServer.handleArpResponse(arpResponse: arpResponse)
        }
    }
    
    private func makeSuperEventProcessor() -> SDLSuperEventProcessor {
        return .init(networkAddress: self.config.networkAddress)
    }
    
    private func handleRegisterSuperAck(registerSuperAck: SDLRegisterSuperAck) async {
        // 需要对数据通过rsa的私钥解码
        guard let key = try? self.rsaCipher.decode(data: Data(registerSuperAck.key)) else {
            SDLLogger.log("[SDLContext] registerSuperAck invalid key")
            let error = SDLError.invalidKey
            self.provider.cancelTunnelWithError(error)
            return
        }
        
        let algorithm = registerSuperAck.algorithm.lowercased()
        let regionId = registerSuperAck.regionID
        self.sessionToken = registerSuperAck.sessionToken
        
        switch algorithm {
        case "aes":
            self.dataCipher = CCAESChiper(key: key)
        case "chacha20":
            self.dataCipher = CCChaCha20Cipher(regionId: regionId, keyData: key)
        default:
            SDLLogger.log("[SDLContext] registerSuperAck invalid algorithm \(algorithm)")
            let error = SDLError.unsupportedAlgorithm(algorithm: algorithm)
            self.provider.cancelTunnelWithError(error)
            return
        }
        
        SDLLogger.log("[SDLContext] registerSuperAck, use algorithm \(algorithm), key len: \(key.count)")
        // 服务器分配的tun网卡信息
        do {
            try await self.setNetworkSettings(config: self.config, dnsServer: DNSHelper.dnsServer)
            SDLLogger.log("[SDLContext] setNetworkSettings successed")
            await self.startPacketReader()
            // 开启权限的定时更新
            await self.whenRegistedSuper()
        } catch let err {
            SDLLogger.log("[SDLContext] setTunnelNetworkSettings get error: \(err)")
            self.provider.cancelTunnelWithError(err)
        }
    }
    
    // 注册成功super的回调函数
    private func whenRegistedSuper() async {
        self.updatePolicyTask?.cancel()
        
        self.updatePolicyTask = Task {
            do {
                while true {
                    try await Task.sleep(for: .seconds(300))
                    SDLLogger.log("[SDLContext] updatePolicyTask execute")
                    await self.policyService.updatePolicy(superService: self.superService)
                }
            } catch let err {
                SDLLogger.log("[SDLContext] updatePolicyTask stop with err: \(err)")
            }
        }
        
        // 启动stun任务
        await self.startStunRequestTask()
    }
    
    private func handleRegisterSuperNak(nakPacket: SDLRegisterSuperNak) {
        let errorMessage = nakPacket.errorMessage
        guard let errorCode = SDLNAKErrorCode(rawValue: UInt8(nakPacket.errorCode)) else {
            return
        }
        
        switch errorCode {
        case .invalidToken, .nodeDisabled:
            self.publishTunnelEvent(code: Int(errorCode.rawValue), message: errorMessage)
            // 报告错误并退出
            let error = NSError(domain: "com.jihe.punchnet.tun", code: -1)
            self.provider.cancelTunnelWithError(error)
            
        case .noIpAddress, .networkFault, .internalFault:
            self.publishTunnelEvent(code: Int(errorCode.rawValue), message: errorMessage)
        }
        SDLLogger.log("[SDLContext] Get a SuperNak message exit")
    }
    
    private func handleEvent(event: SDLEvent) async {
        let processor = self.makeSuperEventProcessor()
        let plan = await processor.makeProcessingPlan(event: event)
        if let logMessage = plan.logMessage {
            SDLLogger.log(logMessage)
        }
        
        switch plan.action {
        case .removeSession(let dstMac):
            await self.sessionManager.removeSession(dstMac: dstMac)
        case .sendRegister(let registerData, let remoteAddresses):
            for remoteAddress in remoteAddresses {
                await self.sendPeerPacket(type: .register, data: registerData, remoteAddress: remoteAddress)
            }
        case .shutdown(let message):
            self.publishTunnelEvent(message: message)
            
            // 报告错误并退出
            let error = NSError(domain: "com.jihe.punchnet.tun", code: -2)
            self.provider.cancelTunnelWithError(error)
        case .none:
            ()
        }
    }
    
    private func doRegisterSuper() async {
        // 注册
        var registerSuper = SDLRegisterSuper()
        registerSuper.clientID = self.config.clientId
        registerSuper.networkID = self.config.networkAddress.networkId
        registerSuper.mac = self.config.networkAddress.mac
        registerSuper.ip = self.config.networkAddress.ip
        registerSuper.maskLen = UInt32(self.config.networkAddress.maskLen)
        registerSuper.hostname = self.config.hostname
        registerSuper.pubKey = self.rsaCipher.pubKey
        registerSuper.accessToken = self.config.accessToken
        
        if let registerSuperData = try? registerSuper.serializedData() {
            SDLLogger.log("[SDLContext] will send register super")
            await self.superService?.send(type: .registerSuper, data: registerSuperData)
        }
    }
    
}

// MARK: DNS service events
extension SDLContextActor {
    private func handleDNSEvent(_ event: SDLDNSService.Event) async {
        switch event {
        case .packet(let packet):
            let nePacket = NEPacket(data: packet, protocolFamily: 2)
            self.provider.packetFlow.writePacketObjects([nePacket])
        }
    }
}

// MARK: 处理从Hole收到的数据
extension SDLContextActor {
    private func handleUDPHoleEvent(_ event: SDLUDPHoleService.Event) async {
        switch event {
        case .ready(let localAddress):
            SDLLogger.log("[SDLContext] udpHole ready: \(localAddress)")
        case .natType(let natType):
            self.setNatType(natType: natType)
            SDLLogger.log("[SDLContext] nat_type is: \(natType)")
        case .packet(let remoteAddress, let message, let source):
            await self.handleUDPHolePacket(remoteAddress: remoteAddress, message: message, source: source)
        case .closed(let error):
            SDLLogger.log("[SDLContext] udpHole closed: \(error)", for: .debug)
        }
    }

    private func handleUDPHolePacket(remoteAddress: SocketAddress, message: SDLHoleMessage, source: SDLUDPHoleKind) async {
        switch message.inboundMessage {
        case .control(let message):
            switch message {
            case .stunReply(_), .stunProbeReply(_):
                SDLLogger.log("[SDLContext] get a stun reply", for: .debug)
            case .register(let register):
                try? await self.handleRegister(remoteAddress: remoteAddress, register: register, source: source)
            case .registerAck(let registerAck):
                await self.handleRegisterAck(remoteAddress: remoteAddress, registerAck: registerAck, source: source)
            }
        case .data(let data):
            try? await self.handleHoleData(data: data)
        }
    }
    
    private func handleRegister(remoteAddress: SocketAddress, register: SDLRegister, source: SDLUDPHoleKind) async throws {
        let networkAddr = config.networkAddress
        SDLLogger.log("[SDLContext] register packet: \(register), network_address: \(networkAddr)")
        
        // 判断目标地址是否是tun的网卡地址, 并且是在同一个网络下
        if register.dstMac == networkAddr.mac && register.networkID == networkAddr.networkId {
            // 回复ack包
            var registerAck = SDLRegisterAck()
            registerAck.networkID = networkAddr.networkId
            registerAck.srcMac = networkAddr.mac
            registerAck.dstMac = register.srcMac
            
            await self.sendPeerPacket(type: .registerAck, data: try registerAck.serializedData(), remoteAddress: remoteAddress)
            // 这里需要建立到来源的会话, 在复杂网络下，通过super-node查询到的nat地址不一定靠谱，需要通过udp包的来源地址作为nat地址
            if let session = Session(dstMac: register.srcMac, natAddress: remoteAddress, addressType: source.convertAddressType()) {
                await self.sessionManager.addSession(session: session)
            } else {
                SDLLogger.log("[SDLContext] didReadRegister get unsupported remoteAddress: \(remoteAddress)", for: .debug)
            }
        } else {
            SDLLogger.log("[SDLContext] didReadRegister get a invalid packet, because dst_ip not matched: \(register.dstMac)")
        }
    }
    
    private func handleRegisterAck(remoteAddress: SocketAddress, registerAck: SDLRegisterAck, source: SDLUDPHoleKind) async {
        // 判断目标地址是否是tun的网卡地址, 并且是在同一个网络下
        let networkAddr = config.networkAddress
        if registerAck.dstMac == networkAddr.mac && registerAck.networkID == networkAddr.networkId {
            if let session = Session(dstMac: registerAck.srcMac, natAddress: remoteAddress, addressType: source.convertAddressType()) {
                await self.sessionManager.addSession(session: session)
            } else {
                SDLLogger.log("[SDLContext] didReadRegisterAck get unsupported remoteAddress: \(remoteAddress)", for: .debug)
            }
        } else {
            SDLLogger.log("[SDLContext] didReadRegisterAck get a invalid packet, because dst_mac not matched: \(registerAck.dstMac)")
        }
    }
    
    private func makeHoleDataProcessor() -> SDLHoleDataProcessor {
        return .init(
            networkAddress: self.config.networkAddress,
            dataCipher: self.dataCipher,
            policyService: self.policyService)
    }
    
    private func handleHoleData(data: SDLData) async throws {
        let processor = self.makeHoleDataProcessor()
        guard let plan = try await processor.makeProcessingPlan(data: data) else {
            return
        }
        
        self.flowTracer.inc(num: plan.inboundBytes, type: .inbound)
        
        switch plan.action {
        case .sendARPReply(let dstMac, let responseData):
            SDLLogger.log("[SDLContext] get arp request packet")
            await self.routeLayerPacket(dstMac: dstMac, type: .arp, data: responseData)
        case .appendARP(let ip, let mac):
            SDLLogger.log("[SDLContext] get arp response packet")
            await self.arpServer.append(ip: ip, mac: mac)
        case .writeToTun(let packetData, let identityID):
            let packet = NEPacket(data: packetData, protocolFamily: 2)
            self.provider.packetFlow.writePacketObjects([packet])
            SDLLogger.log("[SDLContext] hole identity: \(identityID), allow, data count: \(packetData.count)", for: .trace)
        case .requestPolicy(let srcIdentityID):
            SDLLogger.log("[SDLContext] not found identity: \(srcIdentityID) ruleMap", for: .debug)
            if let queryData = await self.policyService.identifyStore.makePolicyRequest(srcIdentityId: srcIdentityID, dstIdentityId: self.config.identityId) {
                await self.superService?.send(type: .policyRequest, data: queryData)
            }
        case .none:
            ()
        }
    }
    
}

// MARK: 和Stun相关的心跳机制
extension SDLContextActor {
    
    // MARK: -- StunRequestTask
    private func startStunRequestTask() async {
        self.stunRequestTask?.cancel()
        self.stunRequestTask = nil

        // 处理心跳逻辑
        self.stunRequestTask = Task { [weak self] in
            let timerStream = SDLAsyncTimerStream()
            timerStream.start(interval: .seconds(8))
            
            for await _ in timerStream.stream {
                if Task.isCancelled {
                    break
                }
                
                let probeReply = try? await self?.ipv6AssistClient?.probe(requestTimeout: .seconds(3))
                if Task.isCancelled {
                    break
                }

                if let v6Info = probeReply?.v6Info, let v6Address = SDLUtil.ipv6DataToString(v6Info.v6) {
                    SDLLogger.log("[SDLContext] probe ipv6 address: \(v6Address)")
                } else {
                    SDLLogger.log("[SDLContext] probe ipv6 address: empty")
                }

                if Task.isCancelled {
                    break
                }

                await self?.sendStunRequest(v6Info: probeReply?.v6Info)
            }
            
            SDLLogger.log("[SDLContext] udp stunRequestTask cancel")
        }
    }
    
    private func sendStunRequest(v6Info: SDLV6Info?) async {
        guard let sessionToken = self.sessionToken else {
            return
        }
        
        var stunRequest = SDLStunRequest()
        stunRequest.clientID = self.config.clientId
        stunRequest.networkID = self.config.networkAddress.networkId
        stunRequest.ip = self.config.networkAddress.ip
        stunRequest.mac = self.config.networkAddress.mac
        stunRequest.natType = UInt32(self.natType.rawValue)
        stunRequest.sessionToken = sessionToken
        
        if let v6Info {
            stunRequest.v6Info = v6Info
        }
        
        if let stunData = try? stunRequest.serializedData() {
            await self.sendSuperPacket(type: .stunRequest, data: stunData)
        }
    }
}

// MARK: NEPacketTunnelProvider相关的逻辑
extension SDLContextActor {
    
    // 开始读取数据, 用单独的线程处理packetFlow
    private func startPacketReader() async {
        if self.packetReaderService == nil {
            self.packetReaderService = SDLPacketReaderService(provider: self.provider) { [weak self] event in
                await self?.handlePacketReaderEvent(event)
            }
        }
        await self.packetReaderService?.start()
    }

    private func handlePacketReaderEvent(_ event: SDLPacketReaderService.Event) async {
        switch event {
        case .packet(let packet):
            await self.dealTunPacket(packet: packet)
        }
    }
    
    // 取消出口节点的时候，ip地址为: 0.0.0.0
    public func updateExitNode(exitNodeIp: String) async throws {
        if let ip = SDLUtil.ipv4StrToInt32(exitNodeIp), ip > 0 {
            self.config.exitNode = .init(exitNodeIp: ip)
        } else {
            self.config.exitNode = nil
        }
        try await self.setNetworkSettings(config: config, dnsServer: DNSHelper.dnsServer)
    }
    
    // MARK: 网络改变时需要重新配置网络信息
    private func setNetworkSettings(config: SDLConfiguration, dnsServer: String) async throws {
        let networkAddress = config.networkAddress
        
        // 配置路由规则
        var routes: [NEIPv4Route] = [
            NEIPv4Route(destinationAddress: networkAddress.netAddress, subnetMask: networkAddress.maskAddress),
            NEIPv4Route(destinationAddress: dnsServer, subnetMask: "255.255.255.255"),
        ]
        
        // 如果存在出口节点配置，则接管系统默认留有
        if config.exitNode != nil {
            routes.append(.default())
        }
        
        // Add code here to start the process of connecting the tunnel.
        let networkSettings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: "8.8.8.8")
        networkSettings.mtu = 1250
        
        // 设置网卡的DNS解析
        let networkDomain = networkAddress.networkDomain
        let dnsSettings = NEDNSSettings(servers: [dnsServer])

        dnsSettings.searchDomains = [networkDomain]
        dnsSettings.matchDomains = [networkDomain, ""]
        // 设置为 false 允许系统在补全 Search Domain 时也能匹配到此设置
        dnsSettings.matchDomainsNoSearch = false
        
        networkSettings.dnsSettings = dnsSettings
        
        let ipv4Settings = NEIPv4Settings(addresses: [networkAddress.ipAddress], subnetMasks: [networkAddress.maskAddress])
        // 设置路由表
        ipv4Settings.includedRoutes = routes
        
        // 配置要排除的路由
        ipv4Settings.excludedRoutes = self.getIpv4ExcludeRoutes()
        
        networkSettings.ipv4Settings = ipv4Settings
        // 网卡配置设置必须成功
        try await self.provider.setTunnelNetworkSettings(networkSettings)
    }
    
    private func getIpv4ExcludeRoutes() -> [NEIPv4Route] {
        // 要排除的路由表
        let dnsServers = SDLUtil.getMacOSSystemDnsServers()
        var ipv4DnsServers = dnsServers.filter {!$0.contains(":")}
        
        // 增加常见的dns服务
        let commonDnsServers = [
            "8.8.8.8",
            "8.8.4.4",
            "223.5.5.5",
            "223.6.6.6",
            "114.114.114.114"
        ]
        for ip in commonDnsServers {
            if !ipv4DnsServers.contains(ip) {
                ipv4DnsServers.append(ip)
            }
        }
        
        return ipv4DnsServers.map { NEIPv4Route(destinationAddress: $0, subnetMask: "255.255.255.255") }
    }
    
    // 处理读取的每个数据包, Tun收到的包的一级路由
    private func dealTunPacket(packet: IPPacket) async {
        let router = SDLTunPacketRouter(networkAddress: self.config.networkAddress, exitNode: self.config.exitNode)
        
        let decision = router.route(packet: packet)
        
        // 外部出去的数据，需要建立FlowSession
        // 外部数据进来的时候需要查找
        if decision.shouldTrackFlow, let flowSession = packet.flowSession() {
            await self.policyService.flowSessionManager.updateSession(flowSession)
            //SDLLogger.shared.log("[SDLContext] flow_session: \(flowSession)", level: .debug)
        }
        
        await self.handleTunRouteDecision(decision)
    }
    
    private func handleTunRouteDecision(_ decision: SDLTunPacketRouter.RouteDecision) async {
        switch decision {
        case .loopback(let ipPacketData):
            let nePacket = NEPacket(data: ipPacketData, protocolFamily: 2)
            self.provider.packetFlow.writePacketObjects([nePacket])
        case .cloudDNS(let name, let ipPacketData):
            SDLLogger.log("[SDLContext] get cloud dns request: \(name)")
            await self.dnsService?.forward(ipPacketData: ipPacketData)
        case .localDNS(let name, let payload, let tracker):
            SDLLogger.log("[SDLContext] get local dns request: \(name)")
            await self.dnsService?.queryLocal(tracker: tracker, dnsPayload: payload)
        case .forwardToNextHop(let ip, let type, let data, let kind):
            await self.forwardPacketToNextHop(ip: ip, type: type, data: data, kind: kind)
        case .drop(let reason):
            SDLLogger.log("[SDLContext] drop tun packet, reason: \(reason.rawValue)", for: .trace)
        }
    }
    
    private func forwardPacketToNextHop(ip: UInt32, type: LayerPacket.PacketType, data: Data, kind: SDLTunPacketRouter.ForwardKind) async {
        switch kind {
        case .sameNetwork:
            SDLLogger.log("[SDLContext] dstIp: \(asIpAddress(ip)) same network", for: .trace)
        case .exitNode, .dnsExitNode:
            SDLLogger.log("[SDLContext] use exit_node: \(asIpAddress(ip))", for: .trace)
        }
        
        // 查找arp缓存中是否有目标mac地址
        if let dstMac = await self.arpServer.query(ip: ip) {
            SDLLogger.log("[SDLContext] dstIp: \(asIpAddress(ip)), dst_mac is: \(SDLUtil.formatMacAddress(mac: dstMac))", for: .trace)
            await self.routeLayerPacket(dstMac: dstMac, type: type, data: data)
        }
        else {
            SDLLogger.log("[SDLContext] dstIp: \(asIpAddress(ip)) arp query not found, broadcast", for: .trace)
            if let arpRequest = try? await self.arpServer.makeArpRequest(targetIp: ip) {
                await self.superService?.send(type: .arpRequest, data: arpRequest)
            }
        }
    }
    
    private func makeLayerPacketForwarder() -> SDLLayerPacketForwarder {
        return .init(
            networkAddress: self.config.networkAddress,
            identityID: self.config.identityId,
            dataCipher: self.dataCipher,
            sessionManager: self.sessionManager
        )
    }
    
    private func routeLayerPacket(dstMac: Data, type: LayerPacket.PacketType, data: Data) async {
        // 将数据封装层2层的数据包
        // 构造数据包
        let forwarder = self.makeLayerPacketForwarder()
        guard let plan = try? await forwarder.makeDeliveryPlan(dstMac: dstMac, type: type, data: data) else {
            return
        }
        
        // 广播地址不要去尝试打洞
        switch plan {
        case .superNode(let payload):
            // 通过super_node进行转发
            await self.sendSuperPacket(type: .data, data: payload)
        case .peer(let payload, let session):
            // 通过session发送到对端
            SDLLogger.log("[SDLContext] step 5 send packet by session: \(session)", for: .trace)
            await self.sendPeerPacket(type: .data, data: payload, remoteAddress: session.natAddress)
            self.flowTracer.inc(num: payload.count, type: .p2p)
        case .superNodeAndPunch(let payload, let request):
            // 通过super_node进行转发
            await self.sendSuperPacket(type: .data, data: payload)
            SDLLogger.log("[SDLContext] step 5 send packet by super: \(self.config.stunSocketAddress)", for: .trace)
            // 流量统计
            self.flowTracer.inc(num: payload.count, type: .forward)
            
            // 尝试打洞
            if let queryData = await self.puncherActor.makeQueryInfoRequest(request: request) {
                await self.superService?.send(type: .queryInfo, data: queryData)
            }
        }
    }
    
}